Structural Biology Seminar - Wed., Nov. 20
|Event Date:||November 20, 2013|
|Location:||LILY 1-117, WL campus
Only a little more than decade ago, it was proposed to use ultra-short, ultra-bright x-ray pulses from x-ray free electron lasers (XFELs) for coherent x-ray diffraction imaging (CDXI) and atomic-resolution structure determination of individual biological molecules (Neutze, et al., Nature 2000). In this “diffract-and-destroy” concept, a molecule is exposed to an ultra-short, ultra-bright x-ray pulse (~100 fs, 1012 photons per pulse in a ~100 nm sized focal spot), which produces a measurable x-ray diffraction pattern before the molecule is destroyed by radiation damage. This concept enables, in principle, to obtain atomic-resolution structure information from membrane proteins and other materials that do no form large crystals. (Protein crystals are used in traditional x-ray crystallography at synchrotron sources to mitigate the radiation damage problems that occur in diffraction experiments with longer x-ray exposure time.) This proposed concept was one of the primary motivations for building the Linear Coherent Light Source (LCLS) at SLAC, the world’s first 4th generation x-ray source and hard XFEL that started operations in the fall of 2009.
Here we give an overview of this imaging concept and describe some of the significant experimental challenges in sample preparation, sample introduction, high-rate imaging and data analysis. We present an overview of the first proof-of-concept results obtained from CXDI with XFELs and describe some of the most recent experiments and results in biological imaging.